FIG. 6.

Expression of EYFP in HeLa cells stably transformed with the expression cassette shown in Fig. 2B. HeLa cells were transfected with the linearized plasmids with the cassette flanked by the test DNA fragments together with a plasmid expressing the G418 resistance gene at a molar ratio of 4:1. Cell colonies resistant to G418 were obtained by culturing the cells with growth medium containing G418 (500 mg/ml). At 4 weeks after the transfection, fluorescence of the cell colonies was observed under the UV microscope. Typical photos of two cell clones (clones A and B) containing the test cassette are presented.